The overall objectives of this project is to increase our understanding of the interaction of ultrasound with tissue. Two complimentary approaches are taken: (a) From studies of the acoustic properties of tissues, physical processes and effects can be deduced. (b) From direct observations of biological effects we can postulate and test for the responsible mechanisms. Our specific goals for the coming year include (1) Studies of absorption of sound in tissue (2) Exploration of nonlinear phenomena in tissue (3) Testing of the cavitation hypothesis for the effects of ultrasound on plant roots (4) Studies of the physical mechanisms potentially responsible for the effects of ultrasound on Drosophila (5) Exploration of the possibility of increased metastasis by ultrasonic irradiation of malignant tissue. BIBLIOGRAPHIC REFERENCES: "Histomorphology of Ultrasonic Renal Injury," A. Elbadawi, C.A. Linke, E.L. Carstensen, and C.W. Fridd, Archives of Pathology and Laboratory Medicine, 100:199-205, 1976. "Dielectric Properties of Shepadex and its Water of Hydration," by George T. Koide and Edwin L. Carstensen, J. Phys. Chem., 80:55-59, 1976.